Perovskite light emitting device containing exciton buffer layer and method for manufacturing same

ABSTRACT

Provided are a perovskite light emitting device containing an exciton buffer layer, and a method for manufacturing the same. A light emitting device of the present invention comprises: an exciton buffer layer in which a first electrode, a conductive layer disposed on the first electrode and comprising a conductive material, and a surface buffer layer containing fluorine-based material having lower surface energy than the conductive material are sequentially deposited; a light-emitting layer disposed on the exciton buffer layer and containing a perovskite light-emitter; and a second electrode disposed on the light-emitting layer. Accordingly, a perovskite is formed with a combined FCC and BSS crystal structure in a nanoparticle light-emitter. The present invention can also form a lamellar or layered structure in which an organic plane and an inorganic plane are alternatively deposited; and an exciton can be bound by the inorganic plane, thereby being capable of expressing high color purity.

TECHNICAL FIELD

The present invention relates to a light emitting device, and moreparticularly, to a perovskite light emitting device including an excitonbuffer layer and a method for manufacturing the same.

BACKGROUND ART

The current major trend in the display market has shifted fromconventional high-efficiency and high-resolution-oriented displaystoward displays with vivid image qualities which aim to realize naturalcolors with high color purity. In this sense, organiclight-emitter-based organic light emitting diode (OLED) devices havebeen developed rapidly and research on inorganic quantum-dot LEDs havingimproved color purity has been actively conducted as anotheralternative. However, both of the organic light-emitter and theinorganic quantum-dot light-emitter have inherent limits in terms ofmaterials.

The conventional organic light-emitters have an advantage of highefficiency but have a drawback in that they have poor color purity dueto a wide spectrum. The inorganic quantum-dot light-emitters have beenknown to have good color purity, but have a drawback in that their colorpurity may be degraded because it is difficult to uniformly control aquantum dot size due to light emission caused by a quantum size effectas emitted light is shifted toward blue. Also, the two light-emittershave a drawback in that they are very expensive. Therefore, there is aneed for a novel type of organic-inorganic-hybrid light-emitter to makeup for the drawbacks and keep the advantages of such organic andinorganic light-emitters.

Organic-inorganic-hybrid materials have advantages in that they have alow manufacturing cost and may be simply manufactured and applied tomanufacture devices, and have both advantages of an organic materialwhose optical and electrical properties may be easily controlled and aninorganic material having high charge mobility and mechanical andthermal stability. Therefore, the organic-inorganic-hybrid materialshave come into the spotlight in both scientific and industrial aspects.

Among these, an organic-inorganic-hybrid perovskite material has a highpotential for development as a light-emitter because such a material hashigh color purity, its colors may be simply adjusted, and has lowsynthesis cost. Because the organic-inorganic-hybrid perovskite materialhaving high color purity has a lamellar structure in which atwo-dimensional (2D) plane of an inorganic substance is interposedbetween 2D planes of an organic substance, and has a high difference indielectric constant between the inorganic substance and the organicsubstance, excitons (ε_(organic)≈2.4, and ε_(inorganic)≈6.1) areconfined to an inorganic layer. Accordingly, such a configuration isformed because the organic-inorganic-hybrid perovskite material has highcolor purity (a full width at half maximum (FWHM)≈20 nm).

A conventional material having a perovskite structure (ABX₃) is aninorganic metal oxide.

Such an inorganic metal oxide is generally a compound in which cationsof metals (alkali metals, alkaline earth metals, transition metals,lanthanides, etc.) having different sizes, such as Ti, Sr, Ca, Cs, Ba,Y, Gd, La, Fe, Mn, etc., are positioned at the A and B sites, oxygenanions are positioned at the X site, and the metal cations at the B siteare bound to the oxygen anions at the X site in the form of acorner-sharing octahedron with 6-fold coordination. Examples of theinorganic metal oxide include SrFeO₃, LaMnO₃, CaFeO₃, etc.

On the other hand, the organic-inorganic-hybrid perovskite has quitedifferent compositions than the inorganic metal oxide perovskitematerial because it has an ABX₃ structure in which organic ammonium(RNH₃) cations are positioned at the A site and halides (Cl, Br, I) arepositioned as the X site, thereby forming an organic metal halideperovskite material.

Also, the characteristics of the material vary depending on a differencein such constituent materials. Typically, because the inorganic metaloxide perovskite exhibits characteristics such as superconductivity,ferroelectricity, colossal magnetoresistance, etc., the inorganic metaloxide perovskite has been generally researched to apply it to sensors,fuel cells, memory devices, etc. For example, yttrium barium copperoxide has superconducting or insulating characteristics, depending onoxygen content.

On the other hand, because the organic-inorganic-hybrid perovskite (ormetal halide perovskite) has a structure very similar to the lamellarstructure in that an organic plane (or an alkali metal plane) and aninorganic plane are alternately stacked, excitons are confined in theinorganic plane. Therefore, the organic-inorganic-hybrid perovskite mayessentially become an ideal light-emitter that emits light with veryhigh color purity due to a crystalline structure itself rather than thesize of the material.

When the organic-inorganic-hybrid perovskite includes a chromophore(generally having a conjugated structure) in which organic ammonium hasa smaller band gap than a central metal and a halogen crystallinestructure (BX3), light is emitted from the organic ammonium. As aresult, the organic-inorganic-hybrid perovskite is not suitable as alight emitting layer because it does not emit light with high colorpurity and has a wider full width at half maximum of 100 nm or more inan emission spectrum. Thus, the organic-inorganic-hybrid perovskite isnot highly suitable for light-emitters with high color purity, ashighlighted in this patent. Therefore, to fabricate the light-emitterswith high color purity, it is important for the organic ammonium toinclude no chromophore and emit light from an inorganic material latticecomposed of a central metal-halogen element. That is, this patent hasfocused on the development of light-emitters with high color purity andhigh efficiency in which light is emitted from the inorganic materiallattice. For example, Korean Patent Publication No. 10-2001-0015084(published on Feb. 26, 2001) discloses an electroluminescence device inwhich a dye-containing organic-inorganic mixed material is formed in theform of a thin film rather than particles to be used as a light emittinglayer, but light is not emitted from a perovskite lattice structure.

However, although the organic-inorganic-hybrid perovskite may emit lightat a low temperature because it has low exciton binding energy, theorganic-inorganic-hybrid perovskite has a fundamental problem in thatexcitons are dissociated into free charges and quenched without leadingto light emission due to thermal ionization and delocalization of chargecarriers at room temperature. Also, when free charges are recombined toform excitons, the excitons may be quenched by neighboring layers havinghigh conductivity, which makes it impossible to emit light. Accordingly,it is necessary to prevent quenching of the excitons to enhance luminousefficiency and brightness of the organic-inorganic-hybrid perovskiteLEDs.

DISCLOSURE Technical Problem

To solve the above problems, it is an aspect of the present invention toprovide an organic-inorganic-hybrid perovskite-based or inorganic metalhalide perovskite-based light emitting device having improved luminousefficiency and brightness by introducing an exciton buffer layer toprevent excitons from being quenched in an organic-inorganic-hybridperovskite or an inorganic metal halide perovskite material.

Technical Solution

According to one aspect of the present invention, there is provided anorganic-inorganic-hybrid light emitting device including an excitonbuffer layer. The light emitting device includes a first electrode, anexciton buffer layer disposed on the first electrode and including aconductive material and a fluorine-based material having lower surfaceenergy than the conductive material, a light emitting layer includingthe organic-inorganic-hybrid perovskite material, and a second electrodedisposed on the light emitting layer.

The exciton buffer layer may be configured so that a conductive layerincluding the conductive material and a surface buffer layer includingthe fluorine-based material having lower surface energy than theconductive material are sequentially deposited. In this case, thesurface buffer layer may have a thickness of 3 nm or more. The excitonbuffer layer may have a conductivity of, 10⁻⁷ S/cm to 1,000 S/cm, andthe fluorine-based material may have a surface energy of 30 mN/m orless.

Also, a concentration of the fluorine-based material in a second surfaceof the surface buffer layer opposite to a first surface, which is closerto the conductive layer, may be lower than a concentration of thefluorine-based material in the first surface of the surface bufferlayer, and a work function determined for the second surface of theconductive layer may be greater than or equal to 5.0 eV.

The fluorine-based material may be an ionomer including at least one Felement, and the ionomer may be a fluorinated ionomer. Thefluorine-based material may include at least one ionomer selected fromthe group consisting of ionomers having structures represented by thefollowing Formulas 1 to 12:

wherein m is a number ranging from 1 to 10,000,000, x and y are eachindependently a number ranging from 0 to 10, and M⁺ represents Na⁺, K⁺,Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50),NH₄ ⁺, NH₂ ⁺ NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, RCHO⁺ or (where Rrepresents CH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m is a number ranging from 1 to 10,000,000;

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are eachindependently a number ranging from 0 to 20, and M⁺ represents Na⁺, K⁺,Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50),NH₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where Rrepresents CH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are eachindependently a number ranging from 0 to 20, M⁺ represents Na⁺, K⁺, Li⁺,H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50), NH₄⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where Rrepresents CH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, z is a numberranging from 0 to 20, and M⁺ represents Na⁺, K⁺, Li⁺, H⁺,CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50), NH₄ ⁺,NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where R representsCH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are eachindependently a number ranging from 0 to 20, Y represents one selectedfrom —COO⁻M⁺, —SO₃ ⁻NHSO₂CF₃ ⁺, and —PO₃ ²⁻(M⁺)₂, and M⁺ represents Na⁺,K⁺, Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to50), NH₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, and RCHO⁺ (Rrepresents CH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, and M⁺ representsNa⁺, K⁺, Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from0 to 50), NH₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺(where R represents CH₃(CH₂)_(n)—, where n is an integer ranging from 0to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000;

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x is a numberranging from 0 to 20, and M⁺ represents Na⁺, K⁺, Li⁺, H⁺,CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50), NH₄ ⁺,NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where R representsCH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are eachindependently a number ranging from 0 to 20, and M⁺ represents Na⁺, K⁺,Li⁺, H³⁰ , CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to50), NH₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where Rrepresents CH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m and n are 0≤m<10,000,000 and 0<n≤10,000,000, R_(f)═—(CF₂)_(z)—(where z is an integer ranging from 1 to 50, provided that 2 isexcluded), —(CF₂CF₂O)_(z)CF₂CF₂— (where z is an integer ranging from 1to 50), —(CF₂CF₂CF₂O)_(z)CF₂CF₂— (where z is an integer ranging from 1to 50), and M⁺ represents Na⁺, K⁺, Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where nis an integer ranging from 0 to 50), NH₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺,C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where R represents CH₃(CH₂)_(n)—, where n isan integer ranging from 0 to 50); and

wherein m and n are 0≤m<10,000,000 and 0<n≤10,000,000, x and y are eachindependently a number ranging from 0 to 20, Y represents one selectedfrom —SO₃ ⁻M⁺, —COO⁻M⁺, —SO₃ ⁻NHSO₂CF₃ ⁺, and —PO₃ ²⁻(M⁺)₂, and M⁺represents Na⁺, K⁺, Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integerranging from 0 to 50), N₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺,or RCHO⁺ (where R represents CH₃(CH₂)_(n)—, where n is an integerranging from 0 to 50).

Also, the fluorine-based material may include at least one ionomer orfluorinated oligomer selected from the group consisting of ionomers orfluorinated oligomers having structures represented by the followingFormulas 13 to 19.

wherein R₁₁ to R₁₄, R₂₁ to R₂₈, R₃₁ to R₃₈, R₄₁ to R₄₈, R₅₁ to R₅₈, andR₆₁ to R₆₈ are each independently selected from hydrogen, —F, a C₁-C₂₀alkyl group, a C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkyl group substitutedwith one or more —F radicals, a C₁-C₂₀ alkoxy group substituted with oneor more —F radicals, Q₁, —O—(CF₂CF(CF₃)—O)_(n)—(CF₂)_(m)-Q₂ (where n andm are each independently an integer ranging from 0 to 20, provided thatthe sum of n and m is greater than or equal to 1), and —(OCF₂CF₂)_(x)-Q₃(where x is an integer ranging from 1 to 20), where Q₁ to Q₃ representan ion group, where the ion group includes an anionic group and acationic group, the anionic group is selected from PO₃ ²⁻, SO₃ ³¹ ,COO⁻, I⁻, CH3COO⁻, and BO₂ ², the cationic group includes one or more ofa metal ion and organic ion, the metal ion is selected from Na⁺, K⁺,Li⁺, Mg⁺², Zn⁺², and Al⁺³, and the organic ion is selected from H⁺,CH₃(CH₂)_(n1)NH₃ ⁺ (where n1 is an integer ranging from 0 to 50), NH₄ ⁺,NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H5OH⁺, CH₃OH⁺, and RCHO⁺ (where R representsCH₃(CH₂)_(n2)—, and n2 is an integer ranging from 0 to 50);

wherein at least one of R₁₁ to R₁₄, at least one of R₂₁ to R₂₈, at leastone of R₃₁ to R₃₈, at least one of R₄₁ to R₄₈, at least one of R₅₁ toR₅₈, and at least one of R₆₁ to R₆₈ are selected from —F, a C₁-C₂₀ alkylgroup substituted with one or more —F radicals, a C₁-C₂₀ alkoxy groupsubstituted with one or more —F radicals,—O—(CF₂CF(CF₃)—O)_(n)—(CF₂)_(m)-Q₂, and —(OCF₂CF₂)_(x)-Q₃;andX-M^(f) _(n)-M^(h) _(m)-M^(a) _(r)-G   <Formula 19>

wherein X represents an end group;

M^(f) represents a unit derived from a fluorinated monomer obtained bycondensation reaction of perfluoropolyether alcohol, polyisocyanate, andan isocyanate-reactive non-fluorinated monomer;

M^(h) represents a unit derived from a non-fluorinated monomer;

M^(a) represents a unit having a silyl group represented by—Si(Y₄)(Y₅)(Y₆), where Y₄, Y₅ and Y₆ each independently represent asubstituted or unsubstituted C₁-C₂₀ alkyl group, a substituted orunsubstituted C₆-C₃₀ aryl group, or a hydrolysable substituent, providedthat at least one of Y₄, Y₅ and Y₆ is the hydrolysable substituent;

G is a monovalent organic group including a residue of a chain transferagent;

n is a number ranging from 1 to 100;

m is a number ranging from 0 to 100; and

r is a number ranging from 0 to 100;

provided that the sum of n, m and r is at least 2.

The conductive material may include at least one selected from the groupconsisting of a conductive polymer, a metallic carbon nanotube,graphene, a reduced graphene oxide, metal nanowires, semiconductornanowires, carbon nanodots, metal nanodots, and a conductive oxide, andthe conductive polymer may include at least one selected from the groupconsisting of polythiophene, polyaniline, polypyrrole, polystyrene,sulfonated polystyrene, poly(3,4-ethylene dioxythiopene), a self-dopedconductive polymer, and a derivative thereof.

At least one moiety represented by one selected from S(Z₁₀₀) and—Si(Z₁₀₁)(Z₁₀₂)(Z₁₀₃) (where Z₁₀₀, Z₁₀₁, Z₁₀₂, and Z₁₀₃ are eachindependently hydrogen, a halogen atom, a substituted or unsubstitutedC₁-C₂₀ alkyl group, or a substituted or unsubstituted C₁-C₂₀ alkoxygroup) is bound to the metal nanowires, the semiconductor nanowires, thecarbon nanodots, or the metal nanodots.

The conductive oxide may include at least one selected from the groupconsisting of indium tin oxide (ITO), indium zinc oxide (IZO), SnO₂, andInO₂.

The surface buffer layer may further include at least one additiveselected from the group consisting of a carbon nanotube, graphene, areduced graphene oxide, metal nanowires, metal carbon nanodots,semiconductor quantum dots, semiconductor nanowires, and metal nanodots.

The exciton buffer layer may further include a crosslinking agent, andthe crosslinking agent may include at least one functional groupselected from the group consisting of an amine group (—NH₂), a thiolgroup (—SH), and a carboxyl group (—COO—). Also, the crosslinking agentmay include at least one functional group selected from the groupconsisting of diaminoalkane, dithiol, a dicarboxylate, an ethyleneglycol di(meth)acrylate derivative, a methylenebisacrylamide derivative,and divinylbenzene (DVB).

The organic-inorganic-hybrid perovskite may be in the form of particlesor thin films having nanocrystals.

The organic-inorganic-hybrid perovskite may have a structure of A₂BX₄,ABX₄, ABX₃ or A_(n−1)B_(n)X_(3n+1) (where n is an integer ranging from 2to 6).

In this case, A is an organic ammonium material, B is a metal material,and X is a halogen element.

For example, A may be (CH₃NH₃)_(n),((C_(x)H_(2x+1))_(n)NH₃)₂(CH₃NH₃)_(n), (RNH₃)₂, (C_(n)H_(2n+1)NH₃)₂,(CF₃NH₃), (CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n),((C_(x)F_(2x+1))_(n)NH₃)₂, or (C_(n)F_(2n+1)NH₃)₂ (where n is an integergreater than or equal to 1, and x is an integer greater than or equal to1). Also, B may be a divalent transition metal, a rare earth metal, analkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or acombination thereof. In this case, the rare earth metal may be adivalent rare earth metal. For example, the rare earth metal may be Ge,Sn, Pb, Eu, or Yb. Also, the alkaline earth metal may, for example, beCa or Sr. Also, X may be Cl, Br, I, or a combination thereof. Further,the light emitting device may further include a plurality of alkylhalides surrounding the perovskite nanocrystals.

According to another aspect of the present invention, there is provideda method for manufacturing an organic-inorganic-hybrid perovskite lightemitting device. The manufacturing method includes forming a firstelectrode, forming an exciton buffer layer, in which a conductive layerincluding a conductive material and a surface buffer layer including afluorine-based material are sequentially deposited, on the firstelectrode, forming a light emitting layer, which includes anorganic-inorganic-hybrid perovskite nanoparticle light-emitter includingorganic-inorganic-hybrid perovskite nanocrystals having a lamellarstructure in which an organic substance plane and an inorganic substanceplane are alternately stacked, on the exciton buffer layer, and forminga second electrode on the light emitting layer.

The organic-inorganic-hybrid perovskite may have a structure of A₂BX₄,ABX₄, ABX₃ or A_(n−1)B_(n)X_(3n+1) (where n is an integer ranging from 2to 6).

In this case, A is an organic ammonium material, B is a metal material,and X is a halogen element.

For example, A may be (CH₃NH₃)_(n), ((C_(x)H_(2x+1))_(n)NH₃)₂(CH₃N₃)_(n), (RNH₃)₂, (C_(n)H_(2n+1)NH₃)₂, (CF₃NH₃),(CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n),((C_(x)F_(2x+1))_(n)NH₃)₂, or (C_(n)F_(2n+1)NH₃)₂ (where n is an integergreater than or equal to 1, and x is an integer greater than or equal to1). Also, B may be a divalent transition metal, a rare earth metal, analkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or acombination thereof. In this case, the rare earth metal may be adivalent rare earth metal. For example, the rare earth metal may be Ge,Sn, Pb, Eu, or Yb. Also, the alkaline earth metal may, for example, beCa or Sr. Further, X may be Cl, Br, I, or a combination thereof.

To solve the above problems, according to still another aspect of thepresent invention, there is provided a light emitting device. The lightemitting device may include a first electrode, an exciton buffer layerdisposed on the first electrode and including a conductive material anda fluorine-based material having lower surface energy than theconductive material, a light emitting layer disposed on the excitonbuffer layer and including an inorganic metal halide perovskitematerial, and a second electrode disposed on the light emitting layer.

The exciton buffer layer is characterized by being configured so that aconductive layer including the conductive material and a surface bufferlayer including the fluorine-based material having lower surface energythan the conductive material are sequentially deposited.

The surface buffer layer is characterized by having a thickness of 3 nmor more.

The exciton buffer layer is characterized by having a conductivity of10⁻⁷ S/cm to 1,000 S/cm.

The fluorine-based material is characterized by having a surface energyof 30 mN/m or less.

To solve the above problems, according to yet another aspect of thepresent invention, there is provided a solar cell. Such a solar cell mayinclude a first electrode, a second electrode, an exciton buffer layer,and a photoactive layer interposed between the first electrode and thesecond electrode and including the aforementioned perovskitenanocrystals.

Advantageous Effects

In the perovskite light emitting device including an exciton bufferlayer and the method for manufacturing the same according to the presentinvention, an organic-inorganic-hybrid perovskite (or organic metalhalide perovskite) having a combined FCC and BCC crystalline structurein a nanoparticle light-emitter can be formed, a lamellar structure inwhich an organic plane (or an alkali metal plane) and an inorganic planeare alternatively deposited can be formed, and excitons can be confinedto the inorganic plane, thereby expressing high color purity.

However, technical problems to be solved by the present invention arenot limited to the technical problems described above, and othertechnical problems not disclosed herein will be clearly understood fromthe following description by those skilled in the art.

DESCRIPTION OF DRAWINGS

FIGS. 1A to 1D are cross-sectional views of light emitting devicesmanufactured by a method for manufacturing a light emitting deviceaccording to one exemplary embodiment of the present invention.

FIG. 2 is a schematic diagram showing an effect of an exciton bufferlayer 30 according to one exemplary embodiment of the present invention.

FIG. 3 is a flowchart illustrating a method for manufacturing anorganic-inorganic-hybrid perovskite nanoparticle light-emitter accordingto one exemplary embodiment of the present invention.

FIG. 4 is a schematic diagram showing the method for manufacturing anorganic-inorganic-hybrid perovskite nanoparticle light-emitter accordingto one exemplary embodiment of the present invention.

FIG. 5 is a schematic diagram showing an organic-inorganic-hybridperovskite colloidal nanoparticle and an inorganic metal halideperovskite colloidal nanoparticle according to one exemplary embodimentof the present invention.

FIG. 6 is a schematic diagram of a perovskite nanocrystalline structureaccording to one exemplary embodiment of the present invention.

FIG. 7 is a schematic diagram (a) and an SEM image (b) of a lightemitting device manufactured in Preparative Example 1 of the presentinvention.

FIGS. 8A to 8D are graphs illustrating current-voltage characteristics(a), brightness-voltage characteristics (b), current efficiency-voltagecharacteristics (c), and external quantum efficiency-voltagecharacteristics (d) of each of light emitting devices of PreparativeExamples 1 to 5 and Comparative Example 1.

FIGS. 9A and 9B are graphs illustrating PL lifetime characteristics andstrength characteristics of light emitting devices of PreparativeExamples 6 to 9 of the present invention and Comparative Example 2.

BEST MODE

Hereinafter, preferred embodiments of the present invention will bedescribed in further detail with reference to the accompanying drawingsin order to describe the present invention more clearly. However, thepresent invention is not limited to the embodiments disclosed below, butcan be implemented in various forms. Throughout this specification, likenumbers refer to like elements throughout the description of thefigures.

In this specification, when it is assumed that a layer is referred to asbeing “on” another layer, it can be directly on the layer, and one ormore intervening elements may also be present. Also, in thisspecification, the directional expressions “up,” “upper (portion),”“top,” and the like may be referred to as being “down,” “lower(portion),” “bottom,” and the like based on the criteria of theexpressions. That is, the expression “spatial direction” should beunderstood as a relative direction, but is not restrictively interpretedas a meaning of an absolute direction.

FIGS. 1A to 1D are cross-sectional views of light emitting devicesmanufactured by a method for manufacturing a light emitting deviceaccording to one exemplary embodiment of the present invention. In FIGS.1A to 1D, an organic-inorganic-hybrid perovskite is described asperovskite, but an inorganic halide perovskite may also be applied inthe same manner as in the description of the organic-inorganic-hybridperovskite.

Referring to FIG. 1A, first, a first electrode 20 is formed on asubstrate 10.

The aforementioned substrate 10 serves as a support of an organic lightemitting device, and is composed of a material having a transparentproperty. Also, the aforementioned substrate 10 may be composed of alltypes of flexible materials and hard materials. In this case, thesubstrate 10 is more preferably composed of a flexible material. Inparticular, the material of the aforementioned substrate 10 havingtransparent and flexible properties may include PET, PS, PI, PVC, PVP,PE, etc.

The aforementioned first electrode 20 is an electrode into which holesare injected, and is composed of a material having a conductiveproperty. The material constituting the aforementioned first electrode20 may be a metal oxide, particularly preferably a transparentconductive metal oxide. For example, the aforementioned transparentconductive metal oxide may include ITO, Al-doped ZnO (AZO), Ga-doped ZnO(GZO), In/Ga-doped ZnO (IGZO), Mg-doped ZnO (MZO), Mo-doped ZnO,Al-doped MgO, Ga-doped MgO, F-doped SnO₂, Nb-doped TiO₂, CuAlO₂, etc.

As a deposition process for forming the aforementioned first electrode20, physical vapor deposition (PVD), chemical vapor deposition (CVD),sputtering, pulsed laser deposition (PLD), thermal evaporation, electronbeam evaporation, atomic layer deposition (ALD), and molecular beamepitaxy (MBE) may be used.

Referring to FIG. 1B, an exciton buffer layer 30 including a conductivematerial and a fluorine-based material having lower surface energy thanthe conductive material is formed on the aforementioned first electrode20.

In this case, the aforementioned exciton buffer layer 30 may beconfigured so that a conductive layer 31 including the aforementionedconductive material and a surface buffer layer 32 including theaforementioned fluorine-based material are sequentially deposited, asshown in FIG. 1B.

The aforementioned conductive material may include at least one selectedfrom the group consisting of a conductive polymer, a metallic carbonnanotube, graphene, a reduced graphene oxide, metal nanowires,semiconductor nanowires, a metal grid, metal nanodots, and a conductiveoxide.

The aforementioned conductive polymer may include polythiophene,polyaniline, polypyrrole, polystyrene, sulfonated polystyrene,poly(3,4-ethylene dioxythiopene), a self-doped conductive polymer, and aderivative or combination thereof. The aforementioned derivative maymean that the conductive polymer may further include various componentssuch as sulfonic acid, etc.

For example, the aforementioned conductive polymer may include at leastone selected from the group consisting ofpolyaniline/dodecylbenzenesulfonic acid (Pani:DBSA; see the followingformula), poly(3,4-ethylenedioxythiopene)/poly(4-styrenesulfonate(PEDOT:PSS; see the following formula), polyaniline/Camphor sulfonicacid (Pani:CSA), and polyaniline/poly(4-styrenesulfonate) (PANI:PSS),but the present invention is not limited thereto.

For example, the conductive polymer may includepolyaniline/dodecylbenzenesulfonic acid (Pani:DBSA; see the followingformula), poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate)(PEDOT:PSS; see the following formula), polyaniline/Camphor sulfonicacid (Pani:CSA), polyaniline/poly(4-styrenesulfonate) (PANI:PSS), etc.,but the present invention is not limited thereto.

R may be H or a C1-C10 alkyl group.

The self-doped conductive polymer may have a degree of polymerization of10 to 10,000,000, and may contain a repeating unit represented by thefollowing Formula 21:

wherein 0<m<10,000,000, 0<n<10,000,000, 0≤a≤20, and 0≤b≤20;

at least one of R₁, R₂, R₃, R′₁, R′₂, R′₃, and R′₄ includes an iongroup, and A, B, A′, and B′ are each independently selected from C, Si,Ge, Sn, and Pb;

R₁, R₂, R₃, R′₁, R′₂, R′₃, and R′₄ are each independently selected fromthe group consisting of hydrogen, a halogen, a nitro group, asubstituted or unsubstituted amino group, a cyano group, a substitutedor unsubstituted C₁-C₃₀ alkyl group, a substituted or unsubstitutedC₁-C₃₀ alkoxy group, a substituted or unsubstituted C₆-C₃₀ aryl group, asubstituted or unsubstituted C₆-C₃₀ arylalkyl group, a substituted orunsubstituted C₆-C₃₀ aryloxy group, a substituted or unsubstitutedC₂-C₃₀ heteroaryl group, a substituted or unsubstituted C₂-C₃₀heteroarylalkyl group, a substituted or unsubstituted C₂-C₃₀heteroaryloxy group, a substituted or unsubstituted C₅-C₃₀ cycloalkylgroup, a substituted or unsubstituted C₅-C₃₀ heterocycloalkyl group, asubstituted or unsubstituted C₁-C₃₀ alkyl ester group, and a substitutedor unsubstituted C₆-C₃₀ aryl ester group, provided that a hydrogen orhalogen element is selectively bound to carbon in the formula;

R4 consists of a conjugated conductive polymer chain; and

X and X′ are each independently selected from the group consisting of asimple bond, O, S, a substituted or unsubstituted C₁-C₃₀ alkylene group,a substituted or unsubstituted C₁-C₃₀ heteroalkylene group, asubstituted or unsubstituted C₆-C₃₀ arylene group, a substituted orunsubstituted C₆-C₃₀ arylalkylene group, a substituted or unsubstitutedC₂-C₃₀ heteroarylene group, a substituted or unsubstituted C₂-C₃₀heteroarylalkylene group, a substituted or unsubstituted C₅-C₂₀cycloalkylene group, and a substituted or unsubstituted C₅-C₃₀heterocycloalkylene group, provided that a hydrogen or halogen elementmay be selectively bound to carbon in the formula.

For example, the ion group may include an anionic group selected fromthe group consisting of PO₃ ²⁻, SO3⁻, COO⁻, I⁻, and CH₃COO⁻, and acationic group selected from the group consisting of an metal ionselected from Na⁺, K⁺, Li⁺, Mg⁺², Zn⁺², and Al⁺³, and an organic ionselected from H⁺, NH₄ ⁺, CH₃(—CH₂—)_(n)O⁺ (where n is a natural numberranging from 1 to 50) and making a pair with the anionic group.

For example, one or more of R₁, R₂, R₃, R′₁, R′₂, R′₃, and R′₄ in theself-doped conductive polymer of Formula 100 may each independently befluorine or a group substituted with fluorine, but the present inventionis not limited thereto.

For example, specific examples of the conductive polymer include thefollowing polymers, but the present invention is not limited thereto.

In this specification, specific examples of the unsubstituted alkylgroup may include linear or branched methyl, ethyl, propyl, isobutyl,sec-butyl, tert-butyl, pentyl, isoamyl, hexyl, etc. In this case, one ormore hydrogen atoms included in the aforementioned alkyl group may besubstituted with a halogen atom, a hydroxyl group, a nitro group, acyano group, a substituted or unsubstituted amino group (—NH₂, —NH(R),and —N(R′)(R″) (where R′ and R″ each independently represent an alkylgroup having 1 to 10 carbon atoms), an amidino group, a hydrazine orhydrazone group, a carboxyl group, a sulfonate group, a phosphate group,a C₁-C₂₀ alkyl group, a halogenated C₁-C₂₀ alkyl group, a C₁-C₂₀ alkenylgroup, a C₁-C₂₀ alkynyl group, a C₁-C₂₀ heteroalkyl group, a C₆-C₂₀ arylgroup, a C₆-C₂₀ arylalkyl group, a C₆-C₂₀ heteroaryl group, or a C₆-C₂₀heteroarylalkyl group.

In this specification, the heteroalkyl group means that one or more,preferably 1 to 5 carbon atoms in the main chain of the aforementionedalkyl group are substituted with heteroatoms such as an oxygen atom, asulfur atom, a nitrogen atom, a phosphorus atom, etc.

In this specification, the aryl group refers to a carbocyclic aromaticsystem containing one or more aromatic rings. Here, the aforementionedrings may be attached or fused together in a pendant manner. Specificexamples of the aryl group may include aromatic groups such as phenyl,naphthyl, tetrahydronaphthyl, etc. In this case, one or more hydrogenatoms in the aforementioned aryl group may be substituted withsubstituents like the aforementioned alkyl group.

In this specification, the heteroaryl group refers to a cyclic aromaticsystem that contains 1, 2 or 3 heteroatoms selected from N, O, P, and Sand has 5 to 30 carbon ring atoms as the remaining ring atoms. Here, theaforementioned rings may be attached or fused together in a pendantmanner. Also, one or more hydrogen atoms in the aforementionedheteroaryl group may be substituted with substituents like theaforementioned alkyl group.

In this specification, the alkoxy group refers to a radical —O-alkyl. Inthis case, the alkyl is as defined above. Specific examples of thealkoxy group include methoxy, ethoxy, propoxy, isobutyloxy,sec-butyloxy, pentyloxy, isoamyloxy, hexyloxy, etc. Here, one or morehydrogen atoms in the aforementioned alkoxy group may be substitutedwith substituents like the aforementioned alkyl group.

As a substituent used in the present invention, a heteroalkoxy groupessentially refers to the aforementioned alkoxy, except that one or moreheteroatoms, for example, oxygen, sulfur or nitrogen, may be present inan alkyl chain. For example, the heteroalkoxy group includesCH₃CH₂OCH₂CH₂O—, C₄H₉OCH₂CH₂OCH₂CH₂O—, CH₃O(CH₂CH₂O)_(n)H, etc.

In this specification, the arylalkyl group means that some of hydrogenatoms in the aryl group as defined above are substituted with radicalssuch as a lower alkyl, for example, methyl, ethyl, propyl, etc. Forexample, the arylalkyl group includes benzyl, phenylethyl, etc. One ormore hydrogen atoms in the aforementioned arylalkyl group may besubstituted with substituents like the aforementioned alkyl group.

In this specification, the heteroarylalkyl group means that some ofhydrogen atoms in the heteroaryl group are substituted with a loweralkyl group. Here, a definition of the heteroaryl in the heteroarylalkylgroup is as described above. One or more hydrogen atoms in theaforementioned heteroarylalkyl group may be substituted withsubstituents like the aforementioned alkyl group.

In this specification, the aryloxy group refers to a radical —O-aryl. Inthis case, the aryl is as defined above. Specific examples of thearyloxy group include phenoxy, naphthoxy, anthracenyloxy,phenanthrenyloxy, fluorenyloxy, indenyloxy, etc. In this case, one ormore hydrogen atoms in the aryloxy group may be substituted withsubstituents like the aforementioned alkyl group.

In this specification, the heteroaryloxy group refers to a radical—O-heteroaryl. In this case, the heteroaryl is as defined above.

In this specification, specific examples of the heteroaryloxy groupinclude a benzyloxy group, a phenylethyloxy group, etc. In this case,one or more hydrogen atoms in the heteroaryloxy group may be substitutedwith substituents like the aforementioned alkyl group.

In this specification, the cycloalkyl group refers to a monovalentmonocyclic system having 5 to 30 carbon atoms. One or more hydrogenatoms in the aforementioned cycloalkyl group may be substituted withsubstituents like the aforementioned alkyl group.

In this specification, the heterocycloalkyl group refers to a monovalentmonocyclic system that contains 1, 2 or 3 heteroatoms selected from N,O, P, and S and has 5 to 30 carbon ring atoms as the remaining ringatoms. Here, one or more hydrogen atoms in the aforementioned cycloalkylgroup may be substituted with substituents like the aforementioned alkylgroup.

In this specification, the alkyl ester group refers to a functionalgroup to which an alkyl group and an ester group are bound. In thiscase, the alkyl group is as defined above.

In this specification, the heteroalkyl ester group refers to afunctional group to which a heteroalkyl group and an ester group arebound. In this case, the aforementioned heteroalkyl group is as definedabove.

In this specification, the aryl ester group refers to a functional groupto which an aryl group and an ester group are bound. In this case, thearyl group is as defined above.

In this specification, the heteroaryl ester group refers to a functionalgroup to which a heteroaryl group and an ester group are bound. In thiscase, the heteroaryl group is as defined above.

The amino group used in the present invention refers to —NH₂, —NH(R) or—N(R′)(R″), where R′ and R″ each independently represent an alkyl grouphaving 1 to 10 carbon atoms.

In this specification, the halogen is fluorine, chlorine, bromine,iodine, or astatine. Among these, fluorine is particularly preferred.

The aforementioned metallic carbon nanotube may be a material composedof a purified metallic carbon nanotube itself or a carbon nanotube inwhich metal particles (for example, Ag, Au, Cu, Pt particles, etc.) areattached to inner and/or outer walls of the carbon nanotube.

The aforementioned graphene may have a structure of single-layergraphene having a thickness of approximately 0.34 nm, a few layergraphene having a structure in which 2 to 10 sheets of the single-layergraphene are deposited, or multilayer graphene having a structure inwhich a larger number of sheets of the single-layer graphene than thefew layer graphene are deposited.

The aforementioned metal nanowires and the semiconductor nanowires may,for example, be selected from Ag, Au, Cu, Pt, nickel silicide (NiSi_(x))nanowires, and composite nanowires of two or more types thereof (forexample, an alloy, a core-shell structure, etc.), but the presentinvention is not limited thereto.

Also, the aforementioned semiconductor nanowires may be selected from Sinanowires doped with Si, Ge, B or N, Ge nanowires doped with B or N, andcomposites of two or more types thereof (for example, an alloy, acore-shell structure, etc.), but the present invention is not limitedthereto.

The aforementioned metal nanowires and semiconductor nanowires may havea diameter of 5 nm to 100 nm and a length of 500 nm to 100 μm. In thiscase, the diameter and length of the metal nanowires and semiconductornanowires may be variously selected depending on a method formanufacturing the aforementioned metal nanowires and semiconductornanowires.

The aforementioned metal grid is obtained by forming metallic lineswhich cross each other in the form of net using Ag, Au, Cu, Al, Pt andan alloy thereof In this case, the metal grid may have a line width of100 nm to 100 μm, but a length of the metal grid is not limited. Theaforementioned metal grid may be formed to extrude from a firstelectrode, or may be inserted into the first electrode so that the metalgrid can be formed in a recessed shape.

The aforementioned metal nanodots may be selected Ag, Au, Cu, Pt, andcomposite nanodots of two or more types thereof (for example, an alloy,a core-shell structure, etc.), but the present invention is not limitedthereto.

At least one moiety (where the aforementioned Z₁₀₀, Z₁₀₁, Z₁₀₂, and Z₁₀₃each independently represent hydrogen, a halogen atom, a substituted orunsubstituted C₁-C₂₀ alkyl group, or a substituted or unsubstitutedC₁-C₂₀ alkoxy group) represented by one selected from —S(Z₁₀₀) and—Si(Z₁₀₁)(Z₁₀₂)(Z₃) may be bound to surfaces of the aforementioned metalnanowires, semiconductor nanowires, and metal nanodots. The at least onemoiety represented by one selected from the aforementioned —S(Z₁₀₀) and—Si(Z₁₀₁)(Z₁₀₂)(Z₁₀₃) is a self-assembled moiety. In this case, abinding force between the metal nanowires, the semiconductor nanowiresand the metal nanodots or a binding force between the metal nanowires,semiconductor nanowires and metal nanodots and the first electrode 210through the aforementioned moiety may be enhanced, resulting in furtherimproved electrical characteristics and mechanical strength.

The aforementioned conductive oxide may be one selected from indium tinoxide (ITO), indium zinc oxide (IZO), SnO₂, and InO₂.

A process of forming the aforementioned conductive layer 31 on theaforementioned first electrode 20 may be performed using a spin-coating,casting, Langmuir-Blodgett (LB), ink-jet printing, nozzle printing,slot-die coating, doctor-blade coating, screen printing, dip coating,gravure printing, reverse-offset printing, physical transfer, spraycoating, chemical vapor deposition, or thermal evaporation process.

Also, the conductive layer 31 may be formed by mixing the aforementionedconductive material with a solvent to prepare a mixed solution, applyingthe mixed solution onto the aforementioned first electrode 10 andthermally treating the mixed solution to remove the aforementionedsolvent. In this case, the aforementioned solvent may be a polarsolvent. In this case, the polar solvent may, for example, include atleast one selected from the group consisting of water, an alcohol(methanol, ethanol, n-propanol, 2-propanol, n-butanol, etc.), formicacid, nitromethane, acetic acid, ethylene glycol, glycerol,n-methyl-2-pyrrolidone (NMP), N,N-dimethyl acetamide, dimethyl formamide(DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), ethyl acetate(EtOAc), acetone, and acetonitrile (MeCN).

When the aforementioned conductive layer 31 includes a metallic carbonnanotube, the metallic carbon nanotube may be grown on theaforementioned first electrode 20, or the carbon nanotube dispersed in asolvent may be formed using a solution-based printing method (e.g., aspray coating, spin-coating, dip coating, gravure coating,reverse-offset coating, screen printing, or slot-die coating method).

When the aforementioned conductive layer 31 includes a metallic grid,the metallic grid may be formed by depositing a metal on theaforementioned first electrode 20 under vacuum to form a metal film andpatterning the first electrode 20 in various network shapes usingphotolithography, or by dispersing a metal precursor or metal particlesin a solvent and subjecting the dispersion to a printing method (e.g., aspray coating, spin-coating, dip coating, gravure coating,reverse-offset coating, screen printing, or slot-die coating method).

The aforementioned conductive layer 31 may serve to improve conductivityin the aforementioned exciton buffer layer 30, and may additionallyserve to regulate scattering, reflection and absorption of light toimprove optical extraction or give flexibility to improve mechanicalstrength.

The aforementioned surface buffer layer 32 includes a fluorine-basedmaterial. In this case, the aforementioned fluorine-based material ispreferably a fluorine-based material having lower surface energy thanthe aforementioned conductive material. In this case, the fluorine-basedmaterial may have a surface energy of 30 mN/m or less.

Also, the aforementioned fluorine-based material may have a higherhydrophobic property than the aforementioned conductive polymer.

In this case, a concentration of the aforementioned fluorine-basedmaterial in a second surface 32 b of the aforementioned surface bufferlayer 32 opposite to a first surface 32 a, which is closer to theaforementioned conductive layer 31, may be lower than a concentration ofthe fluorine-based material in the first surface 32 a of the surfacebuffer layer 32.

Therefore, the second surface 32 b of the aforementioned surface bufferlayer 32 may have a work function of 5.0 eV or more. By way of oneexample, the work function measured for the second surface 32 b of theaforementioned surface buffer layer 32 may be in a range of 5.0 eV to6.5 eV, but the present invention is not limited thereto.

The aforementioned fluorine-based material may be a perfluorinatedionomer or a fluorinated ionomer including at least one F element. Inparticular, when the aforementioned fluorine-based material is afluorinated ionomer, a thick buffer layer may be formed, and phaseseparation between the conductive layer 31 and the surface buffer layer32 may be prevented, which makes it possible to form the exciton bufferlayer 30 more uniformly.

The aforementioned fluorine-based material may include at least oneionomer selected from the group consisting of ionomers having structuresrepresented by the following Formulas 1 to 12:

wherein m is a number ranging from 1 to 10,000,000, x and y are eachindependently a number ranging from 0 to 10, and M⁺ represents Na⁺, K⁺,Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50),N₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where Rrepresents CH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m is a number ranging from 1 to 10,000,000;

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are eachindependently a number ranging from 0 to 20, and M⁺ represents Na⁺, K⁺,Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50),N₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where Rrepresents CH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are eachindependently a number ranging from 0 to 20, M⁺ represents Na⁺, K⁺, Li⁺,H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50), N₄⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where Rrepresents CH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, z is a numberranging from 0 to 20, and M⁺ represents Na⁺, K⁺, Li⁺, H⁺,CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50), NH₄ ⁺,NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where R representsCH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are eachindependently a number ranging from 0 to 20, Y represents one selectedfrom —COO⁻M⁺, —SO₃ ⁻NHSO₂CF₃ ⁺, and —PO₃ ²⁻(M⁺)₂, and M⁺ represents Na⁺,K⁺, Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to50), NH₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, and RCHO⁺ (Rrepresents CH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, and M⁺ representsNa⁺, K⁺, Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from0 to 50), N₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺(where R represents CH₃(CH₂)_(n)—, where n is an integer ranging from 0to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000;

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x is a numberranging from 0 to 20, and M⁺ represents Na⁺, K⁺, Li⁺, H⁺,CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50), NH₄ ⁺,NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where R representsCH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are eachindependently a number ranging from 0 to 20, and M⁺ represents Na⁺, K⁺,Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50),N₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where Rrepresents CH₃(CH₂)_(n)—, where n is an integer ranging from 0 to 50);

wherein m and n are 0≤m<10,000,000 and 0<n≤10,000,000, R_(f)=—(CF₂)_(z)—(where z is an integer ranging from 1 to 50, provided that 2 isexcluded), —(CF₂CF₂O)_(z)CF₂CF₂— (where z is an integer ranging from 1to 50), —(CF₂CF₂CF₂O)_(z)CF₂CF₂— (where z is an integer ranging from 1to 50), and M⁺ represents Na⁺, K⁺, Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where nis an integer ranging from 0 to 50), NH₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺,C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where R represents CH₃(CH₂)_(n)—, where n isan integer ranging from 0 to 50); and

wherein m and n are 0≤m<10,000,000 and 0<n≤10,000,000, x and y are eachindependently a number ranging from 0 to 20, Y represents one selectedfrom —SO₃ ⁻M⁺, —COO⁻M⁺, —SO₃ ⁻NHSO₂CF₃ ⁺, and —PO₃ ²⁻(M⁺)₂, and M⁺represents Na⁺, K⁺, Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integerranging from 0 to 50), NH₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺,or RCHO⁺ (where R represents CH₃(CH₂)_(n)—, where n is an integerranging from 0 to 50).

Also, the aforementioned fluorine-based material may include at leastone ionomer or fluorinated oligomer selected from the group consistingof ionomers or fluorinated oligomers having structures represented bythe following Formulas 13 to 19:

wherein R₁₁ to R₁₄, R₂₁ to R₂₈, R₃₁ to R₃₈, R₄₁ to R₄₈, R₅₁ to R₅₈, andR₆₁ to R₆₈ are each independently selected from hydrogen, —F, a C₁-C₂₀alkyl group, a C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkyl group substitutedwith one or more —F radicals, a C₁-C₂₀ alkoxy group substituted with oneor more —F radicals, Q₁, —O—(CF₂CF(CF₃)—O)_(n)—(CF₂)_(m)-Q₂ (where n andm are each independently an integer ranging from 0 to 20, provided thatthe sum of n and m is greater than or equal to 1), and —(OCF₂CF₂)_(x)Q₃(where x is an integer ranging from 1 to 20), where Q₁ to Q₃ representan ion group, where the aforementioned ion group includes an anionicgroup and a cationic group, the aforementioned anionic group is selectedfrom PO₃ ²⁻, SO₃ ⁻, COO⁻, I⁻, CH₃COO⁻, and BO₂ ²⁻, the aforementionedcationic group includes one or more of a metal ion and organic ion, theaforementioned metal ion is selected from Na⁺, K⁺, Li⁺, Mg⁺², Zn⁺², andAl⁺³, and the aforementioned organic ion is selected from H⁺,CH₃(CH₂)_(n1)NH₃ ⁺ (where n1 is an integer ranging from 0 to 50), NH₄ ⁺,NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, and RCHO⁺ (where R representsCH₃(CH₂)_(n2)—, and n2 is an integer ranging from 0 to 50);

wherein at least one of R₁₁ to R₁₄, at least one of R₂₁ to R₂₈, at leastone of R₃₁ to R₃₈, at least one of R₄₁ to R₄₈, at least one of R₅₁ toR₅₈, and at least one of R₆₁ to R₆₈ are selected from —F, a C₁-C₂₀ alkylgroup substituted with one or more —F radicals, a C₁-C₂₀ alkoxy groupsubstituted with one or more —F radicals,—O—(CF₂CF(CF₃)—O)_(n)—(CF₂)_(m)-Q₂, and —(OCF₂CF₂)_(x)-Q₃;andX-M^(f) _(n)-M^(h) _(m)-M^(a) _(r)-G   <Formula 19>

wherein X represents an end group;

M^(f) represents a unit derived from a fluorinated monomer obtained bycondensation reaction of perfluoropolyether alcohol, polyisocyanate, andan isocyanate-reactive non-fluorinated monomer;

M^(h) represents a unit derived from a non-fluorinated monomer;

M^(a) represents a unit having a silyl group represented by—Si(Y₄)(Y₅)(Y₆), where Y₄, Y₅ and Y₆ each independently represent asubstituted or unsubstituted C₁-C₂₀ alkyl group, a substituted orunsubstituted C₆-C₃₀ aryl group, or a hydrolysable substituent, providedthat at least one of Y₄, Y₅ and Y₆ is the aforementioned hydrolysablesubstituent;

G is a monovalent organic group including a residue of a chain transferagent;

n is a number ranging from 1 to 100;

m is a number ranging from 0 to 100; and

r is a number ranging from 0 to 100;

provided that the sum of n, m and r is at least 2.

The aforementioned surface buffer layer 32 may have a thickness of 20 nmto 500 nm, for example, a thickness of 50 nm to 200 nm. When thethickness of the aforementioned surface buffer layer 32 satisfies thisthickness range as described above, excellent work functioncharacteristics, transmittance and flexible characteristics may beprovided.

The aforementioned surface buffer layer 32 may be formed by applying amixed solution including the aforementioned fluorine-based material anda solvent onto the aforementioned conductive layer 31 and thermallytreating the mixed solution.

The exciton buffer layer 30 thus formed may have a thickness of 50 nm to1,000 nm. Conductivity may be improved as the aforementioned conductivelayer 31 is formed, and surface energy may be simultaneously reduced asthe aforementioned surface buffer layer 32 is formed, thereby maximizinglight emission characteristics.

The aforementioned surface buffer layer 32 may further include at leastone additive selected from the group consisting of a carbon nanotube,graphene, a reduced graphene oxide, metal nanowires, metal carbonnanodots, semiconductor quantum dots, semiconductor nanowires, and metalnanodots. When the surface buffer layer 32 further includes theaforementioned additive, improvement of conductivity of theaforementioned exciton buffer layer 30 may be maximized.

Also, the aforementioned surface buffer layer 32 may further include acrosslinking agent including a bis(phenyl azide)-based material. Whenthe aforementioned surface buffer layer 32 further includes theaforementioned crosslinking agent, compositional separation according tothe time and device driving may be prevented. Accordingly, theresistance and work function of the aforementioned exciton buffer layer30 may be reduced to improve stability and reproducibility of the lightemitting device.

The aforementioned bis(phenyl azide)-based material may be a bis(phenylazide)-based material represented by the following Formula 20.

A process of forming the aforementioned surface buffer layer 32 on theaforementioned conductive layer 31 may be performed using aspin-coating, casting, Langmuir-Blodgett (LB), ink-jet printing, nozzleprinting, slot-die coating, doctor-blade coating, screen printing, dipcoating, gravure printing, reverse-offset printing, physical transfer,spray coating, chemical vapor deposition, or thermal evaporationprocess.

However, in a process of forming the aforementioned exciton buffer layer30, the exciton buffer layer 30 may be formed by sequentially depositingthe aforementioned conductive layer 31 and the surface buffer layer 32,as described above, or by mixing the aforementioned conductive materialand the aforementioned fluorine-based material in a solvent to prepare amixed solution, applying the aforementioned mixed solution onto theaforementioned first electrode and thermally treating the firstelectrode.

In this case, as the aforementioned mixed solution is thermally treated,the conductive layer 31 and the surface buffer layer 32 are sequentiallyformed on the aforementioned first electrode 20 through self-assembly.As a result, the process may be simplified.

The aforementioned fluorine-based material may be a material having asolubility of 90% or more, for example, a solubility of 95% or more withrespect to the polar solvent. Examples of the aforementioned polarsolvent may include water, an alcohol (methanol, ethanol, n-propanol,2-propanol, n-butanol, etc.), ethylene glycol, glycerol, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetone, etc., but thepresent invention is not limited thereto.

The aforementioned exciton buffer layer 30 may further include acrosslinking agent.

The crosslinking agent may be added to the aforementioned exciton bufferlayer 30 to prevent the phase separation of constituent materials fromoccurring according to the time and device driving. Also, a decline inefficiency of the exciton buffer layer 30 may be prevented using asolvent to form the aforementioned surface buffer layer 32. Thus, devicestability and reproducibility may be improved.

The aforementioned crosslinking agent may include at least onefunctional group selected from the group consisting of an amine group(—NH₂), a thiol group (—SH), and a carboxyl group (—COO—).

Also, the aforementioned crosslinking agent may include at least oneselected from the group consisting of a bis(phenyl azide)-basedmaterial, a diaminoalkane-based material, a dithiol-based material, adicarboxylate, an ethylene glycol di(meth)acrylate derivative, amethylenebisacrylamide derivative, and divinylbenzene (DVB).

A hole transport layer (not shown) may be formed on the aforementionedexciton buffer layer 30. The aforementioned hole transport layer may beformed using a method optionally selected from various known methodssuch as a vacuum deposition method, a spin-coating method, a castingmethod, an LB (Langmuir Blodgett) method, etc. In this case, when thevacuum deposition method is chosen, the deposition conditions varydepending on a target compound, a desired structure of a layer, andthermal characteristics. However, the deposition conditions may, forexample, be chosen within a deposition temperature of 100° C. to 500°C., a degree of vacuum of 10⁻¹⁰ to 10⁻³ Torr, and a deposition rate of0.01 Å/sec to 100 Å/sec. Meanwhile, when the spin-coating method ischosen, the coating conditions vary depending on a target compound, adesired structure of a layer, and thermal characteristics. However, thecoating conditions may, for example, be chosen within a coating speed of2,000 rpm to 5,000 rpm and a thermal treatment temperature of 80° C. to200° C. (a thermal treatment temperature used to remove a solvent aftercoating).

The hole transport layer material may be selected from materials capableof promoting the transfer of holes, compared to the injection of theholes. The aforementioned hole transport layer may be formed using knownhole transport materials. For example, the hole transport layer materialmay be an amine-based material having an aromatic condensed ring, or atriphenyl amine-based material.

More specifically, examples of the aforementioned hole transportmaterial may include 1,3 -bis(carbazol-9-yl)benzene (MCP),1,3,5-tris(carbazol-9-yl)benzene (TCP),4,4′,4″-tris(carbazol-9-yl)triphenylamine (TCTA),4,4′-bis(carbazol-9-yl)biphenyl (CBP),N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzidine (NPB),N,N′-bis(naphthalen-2-yl)-N,N′-bis(phenyl)-benzidine (β-NPB),N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-2,2′-dimethylbenzidine(αNPD), di-[4,-(N,N-ditolyl-amino)-phenyl]cyclohexane (TAPC),N,N,N′,N′-tetra-naphthalen-2-yl-benzidine (β-TNB) andN4,N4,N4′,N4′-tetra(biphenyl-4-yl)biphenyl-4,4′-diamine (TPD15),poly(9,9-dioctylfluorene-co-bis-N,N′(4-butylphenyl)-bis-N,N′-phenyl-1,4-phenylenediamine)(PFB), poly(9,9′-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine)(TFB),poly(9,9′-dioctylfluorene-co-bis-N,N′-(4-butylphenyl)-bis-N,N′-phenylbenzidine)(BFB),poly(9,9-dioctylfluorene-co-bis-N,N′-(4-methoxyphenyl)-bis-N,N′-phenyl-1,4-phenylenediamine)(PFMO), etc., but the present invention is not limited thereto.

The aforementioned hole transport layer may have a thickness of 5 nm to100 nm, for example, a thickness of 10 nm to 60 nm. When the thicknessof the aforementioned hole transport layer satisfies this thicknessrange as described above, excellent hole transport characteristics maybe obtained without any increase in drive voltage. However, theaforementioned hole transport layer may be omitted in this case.

Also, when it is assumed that the aforementioned hole transport layer isformed, the aforementioned hole transport layer may have a work functionof Z eV. In this case, the aforementioned Z value may be a real numberranging from 5.2 to 5.6, but the present invention is not limitedthereto.

A work function value (Y₁) of the first surface 32 a of the surfacebuffer layer 32 of the aforementioned exciton buffer layer 30 may be ina range of 4.6 to 5.2, for example, in a range of 4.7 to 4.9. Also, awork function value (Y₂) of the second surface 32 b of the surfacebuffer layer 32 of the aforementioned exciton buffer layer 30 may beless than or equal to the work function of the fluorine-based materialincluded in the aforementioned surface buffer layer 32. For example, theaforementioned work function value (Y₂) may be in a range of 5.0 to 6.5,for example, in a range of 5.3 to 6.2, but the present invention is notlimited thereto.

FIG. 2 is a schematic diagram showing an effect of the exciton bufferlayer 30 according to one exemplary embodiment of the present invention.Referring to FIG. 2, it can be seen that the exciton buffer layer 30according to one exemplary embodiment of the present invention may serveto improve hole injection efficiency, block electrons and inhibit thequenching of excitons.

Referring to FIG. 1C, a light emitting layer 40 including theorganic-inorganic-hybrid perovskite light-emitter is formed on theaforementioned exciton buffer layer 30.

FIG. 3 is a flowchart illustrating a method for manufacturing anorganic-inorganic-hybrid perovskite light-emitter according to oneexemplary embodiment of the present invention.

Referring to FIG. 3, the method for manufacturing anorganic-inorganic-hybrid perovskite nanoparticle light-emitter mayinclude preparing a first solution in which an organic-inorganic-hybridperovskite is dissolved in a protic solvent and a second solution inwhich an alkyl halide surfactant is dissolved in an aprotic solvent(S100), and mixing the first solution with the second solution to formnanoparticles (S200).

That is, the organic-inorganic-hybrid perovskite nanoparticlelight-emitter according to the present invention may be manufacturedthrough an inverse nano-emulsion method.

Hereinafter, the manufacturing method will be described in furtherdetail.

First, a first solution in which an organic-inorganic-hybrid perovskiteis dissolved in a protic solvent and a second solution in which an alkylhalide surfactant is dissolved in an aprotic solvent are prepared(S100).

In this case, the protic solvent may include dimethyl formamide, gamma(γ)-butyrolactone, N-methylpyrrolidone, or dimethyl sulfoxide, but thepresent invention is not limited thereto.

In this case, the organic-inorganic-hybrid perovskite may also be amaterial having a 2D crystalline structure. For example, such anorganic-inorganic-hybrid perovskite may have a structure of ABX₃, A₂BX₄,ABX₄ or A_(n−1)B_(n)X_(3n+1) (where n is an integer ranging from 2 to6).

In this case, A is an organic ammonium material, B is a metal material,and X is a halogen element.

For example, A may be (CH₃NH₃)_(n),((C_(x)H_(2x+1))_(n)NH₃)₂(CH₃NH₃)_(n), (RNH₃)₂, (C_(n)H_(2n+1)NH₃)₂,(CF₃NH₃), (CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n),((C_(x)F_(2x+1))_(n)NH₃)₂, or (C_(n)F_(2n+1)NH₃)2 (where n is an integergreater than or equal to 1, and x is an integer greater than or equal to1). Also, B may be a divalent transition metal, a rare earth metal, analkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or acombination thereof. In this case, the rare earth metal may be adivalent rare earth metal. For example, the rare earth metal may be Ge,Sn, Pb, Eu, or Yb. In addition, the alkaline earth metal may, forexample, be Ca or Sr. Further, X may be Cl, Br, I, or a combinationthereof

Meanwhile, such perovskite may be manufactured by combining AX and BX₂at a constant ratio. That is, the first solution may be formed bydissolving AX and BX₂ in a protic solvent at a constant ratio. Forexample, the first solution in which organic-inorganic-hybrid perovskite(A₂BX₃) is dissolved may be prepared by dissolving AX and BX₂ in aprotic solvent at a ratio of 2:1.

In this case, the aprotic solvent may also include dichloroethylene,trichloroethylene, chloroform, chlorobenzene, dichlorobenzene, styrene,dimethyl formamide, dimethyl sulfoxide, xylene, toluene, cyclohexene, orisopropyl alcohol, but the present invention is not limited thereto.

Also, the alkyl halide surfactant may have an alkyl-X structure. In thiscase, a halogen element corresponding to X may include Cl, Br, I, etc.In this case, the alkyl structure may also include an acyclic alkylhaving a structure of C_(n)H_(2n+1), primary, secondary and tertiaryalcohols having a structure of C_(n)H_(2n+1)OH, etc., an alkylaminehaving a structure of alkyl-N (e. g., hexadecyl amine,9-octadecenylamine 1-amino-9-octadecene (C₁₉H₃₇N)), p-substitutedaniline, and phenyl ammonium and fluorine ammonium, but the presentinvention is not limited thereto.

Next, the first solution is mixed with the second solution to formnanoparticles

(S200).

A process of mixing the first solution with the second solution to formthe nanoparticles preferably includes adding the first solution to thesecond solution dropwise. In this case, the second solution may also bestirred. For example, the second solution in which an organic/inorganicperovskite (OIP) is dissolved is added dropwise to the second solutionin which the alkyl halide surfactant is dissolved while stronglystirring to synthesize nanoparticles.

In this case, when the first solution is added dropwise to the secondsolution, the organic/inorganic perovskite (OIP) is precipitated fromthe second solution due to a difference in solubility. Also, a surfaceof the organic/inorganic perovskite (OIP) precipitated from the secondsolution is stabilized by the alkyl halide surfactant to generatewell-dispersed organic/inorganic perovskite nanocrystals (OIP-NCs).Therefore, an organic-inorganic-hybrid perovskite nanoparticlelight-emitter including organic/inorganic perovskite nanocrystals and aplurality of alkyl halide organic ligands surrounding theorganic/inorganic perovskite nanocrystals may be manufactured.

In this case, the aforementioned organic-inorganic-hybrid perovskitecolloidal nanoparticles may have a band gap energy of 1 eV to 5 eV.

Also, the aforementioned organic-inorganic-hybrid perovskitenanoparticles may have a light emission wavelength of 200 nm to 1,300nm.

Meanwhile, the size of such organic/inorganic perovskite nanocrystalsmay be controlled by adjusting a length or shape factor of the alkylhalide surfactant. For example, the adjustment of the shape factor maybe achieved by controlling the size using a linear, tapered or inversetriangular surfactant.

Meanwhile, the size of the organic/inorganic perovskite nanocrystalsthus generated may be in a range of 1 to 900 nm. When theorganic/inorganic perovskite nanocrystals are formed so that the size ofthe organic/inorganic perovskite nanocrystals is greater than 900 nm,the organic/inorganic perovskite nanocrystals may have a fundamentalproblem in that excitons are dissociated into free charges and quenchedin the large nanocrystals without leading to light emission due tothermal ionization and delocalization of charge carriers.

FIG. 4 is a schematic diagram showing a method for manufacturing anorganic-inorganic-hybrid perovskite nanoparticle light-emitter accordingto one exemplary embodiment of the present invention using an inversenano-emulsion method.

Referring to FIG. 4(a), a first solution in which anorganic-inorganic-hybrid perovskite is dissolved in a protic solvent isadded dropwise to a second solution in which an alkyl halide surfactantis dissolved in an aprotic solvent.

In this case, the protic solvent may include dimethyl formamide,γ-butyrolactone, N-methylpyrrolidone, or dimethyl sulfoxide, but thepresent invention is not limited thereto.

In this case, the organic-inorganic-hybrid perovskite may have astructure of ABX₃, A₂BX₄, ABX₄ or A_(n−1)B_(n)X_(3n+1) (where n is aninteger ranging from 2 to 6).

In this case, A is an organic ammonium material, B is a metal material,and X is a halogen element.

For example, A may be (CH₃NH₃)_(n),((C_(x)H_(2x+1))_(n)NH₃)₂(CH₃NH₃)_(n), (RNH₃)₂, (C_(n)H_(2n+1)NH₃)₂,(CF₃NH₃), (CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂, or (C_(n)F_(2n+1)NH₃)₂ (where n is an integer greaterthan or equal to 1, and x is an integer greater than or equal to 1).Also, B may be a divalent transition metal, a rare earth metal, analkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or acombination thereof. In this case, the rare earth metal may be adivalent rare earth metal. For example, the rare earth metal may be Ge,Sn, Pb, Eu, or Yb. Also, the alkaline earth metal may, for example, beCa or Sr. Further, X may be Cl, Br, I, or a combination thereof.

Meanwhile, in this case, the structures of perovskite may be formed bycombining AX and BX₂ at different ratios. For example, the firstsolution in which organic-inorganic-hybrid perovskite (A₂BX₃) isdissolved may be prepared by dissolving AX and BX₂ in a protic solventat a ratio of 2:1.

Meanwhile, as a synthesis example of AX in this case, when A is CH₃NH₃and X is Br, CH₃NH₃Br may be obtained by dissolving methylamine (CH₃NH₂)and hydrobromic acid (HBr) under a nitrogen atmosphere and evaporatingthe solvent.

Referring to FIG. 4(b), when the first solution is added to the secondsolution, the organic-inorganic-hybrid perovskite is precipitated fromthe second solution due to a difference in solubility, and a surface ofsuch precipitated organic-inorganic-hybrid perovskite is stabilized asthe alkyl halide surfactant surrounds the organic-inorganic-hybridperovskite. At the same time, an organic-inorganic-hybrid perovskitenanoparticle light-emitter 100 including the well-dispersedorganic-inorganic-hybrid perovskite nanocrystals is generated. In thiscase, the surfaces of the organic-inorganic-hybrid perovskitenanocrystals are surrounded by organic ligands that are alkyl halides.

Next, the organic-inorganic-hybrid perovskite nanoparticle light-emittermay be obtained by applying heat to the protic solvent including theorganic-inorganic-hybrid perovskite nanoparticle light-emitter 100dispersed in the aprotic solvent in which the alkyl halide surfactant isdissolved in order to selectively evaporate the protic solvent or byadding to a co-solvent capable of dissolving both of the protic solventand the aprotic solvent to selectively extract the protic solventincluding the nanoparticles from the aprotic solvent.

The organic-inorganic-hybrid perovskite nanoparticle light-emitteraccording to one exemplary embodiment of the present invention will bedescribed.

FIG. 5 is a schematic diagram showing an organic-inorganic-hybridperovskite colloidal nanoparticle light-emitter and an inorganic metalhalide perovskite colloidal nanoparticle light-emitter according to oneexemplary embodiment of the present invention.

In this case, FIG. 5 shows organic-inorganic-hybrid perovskite colloidalnanoparticles. Here, when the organic-inorganic-hybrid perovskite ofFIG. 5 is exchanged with an inorganic metal halide perovskite, inorganicmetal halide colloidal nanoparticles are formed, and thus a descriptionthereof is the same as described above.

Referring to FIG. 5, the light-emitter according to one exemplaryembodiment of the present invention includes, as theorganic-inorganic-hybrid perovskite nanoparticles (or inorganic metalhalide perovskite), 2D organic-inorganic-hybrid perovskite nanocrystals110 having a lamellar structure in which organic substance planes (oralkali metal planes) and inorganic substance planes are alternatelystacked.

Such a 2D organic-inorganic-hybrid perovskite may have a structure ofABX₃, A₂BX₄, ABX₄ or A_(n−1)B_(n)X_(3n+1) (where n is an integer rangingfrom 2 to 6).

In this case, A is an organic ammonium material, B is a metal material,and X is a halogen element.

For example, A may be (CH₃NH₃)_(n),((C_(x)H_(2x+1))_(n)NH₃)₂(CH₃NH₃)_(n), (RNH₃)₂, (C_(n)H_(2n+1)NH₃)₂,(CF₃NH₃), (CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n),((C_(x)F_(2x+1))_(n)NH₃)₂, or (C_(n)F_(2n+1)NH₃)₂ (where n is an integergreater than or equal to 1, and x is an integer greater than or equal to1)). Also, B may be a divalent transition metal, a rare earth metal, analkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or acombination thereof. In this case, the rare earth metal may be adivalent rare earth metal. For example, the rare earth metal may be Ge,Sn, Pb, Eu, or Yb. Also, the alkaline earth metal may, for example, beCa or Sr. Further, X may be Cl, Br, I, or a combination thereof.

Meanwhile, the organic-inorganic-hybrid perovskite nanoparticlelight-emitter 100 according to the present invention may further includea plurality of organic ligands 120 surrounding the aforementionedorganic-inorganic-hybrid perovskite nanocrystals 110. In this case, theorganic ligands 120 may include an alkyl halide as a material used as asurfactant. Therefore, the alkyl halide used as the surfactant becomesan organic ligand surrounding surfaces of the organic-inorganic-hybridperovskite nanocrystals in order to stabilize a surface of theprecipitated organic-inorganic-hybrid perovskite, as described above.

Meanwhile, when the length of such an alkyl halide surfactant is short,an increase in size of nanocrystals to be formed may be caused, therebyforming the nanocrystals having a size of more than 900 nm. In thiscase, the nanocrystals may have a fundamental problem in that excitonsare dissociated into free charges and quenched in the large nanocrystalswithout leading to light emission due to thermal ionization anddelocalization of charge carriers.

That is, the size of the organic-inorganic-hybrid perovskitenanocrystals to be formed is inversely proportional to the length of thealkyl halide surfactant used to form such nanocrystals.

Therefore, the size of the organic-inorganic-hybrid perovskitenanocrystals to be formed using an alkyl halide having a length greaterthan or equal to a predetermined length as the surfactant may becontrolled to a size less than or equal to a predetermined size. Forexample, organic-inorganic-hybrid perovskite nanocrystals having a sizeof 900 nm or less may be formed using octadecyl-ammonium bromide as thealkyl halide surfactant.

Also, the inorganic metal halide perovskite may have a structure ofABX₃, A₂BX₄, ABX₄ or A_(n−1)Pb_(n)I_(3n+1) (where n is an integerranging from 2 to 6).

In this case, A may be an alkali metal, B may be a divalent transitionmetal, a rare earth metal, an alkaline earth metal, Pb, Sn, Ge, Ga, In,Al, Sb, Bi, Po, or a combination thereof, and X may be Cl, Br, I or acombination thereof In this case, the rare earth metal may, for example,be Ge, Sn, Pb, Eu, or Yb. Also, the alkaline earth metal may, forexample, be Ca or Sr.

Also, the inorganic metal halide perovskite colloidal nanoparticlesaccording to the present invention may further include a plurality oforganic ligands surrounding the aforementioned inorganic metal halideperovskite nanocrystalline structure. Such organic ligands may includean alkyl halide.

FIG. 6 is a schematic diagram of a perovskite nanocrystalline structureaccording to one exemplary embodiment of the present invention.

The structures of the organic-inorganic-hybrid perovskite nanocrystaland inorganic metal halide perovskite nanocrystal are shown together inFIG. 6.

Referring to FIG. 6, it can be seen that the organic-inorganic-hybridperovskite (or inorganic metal halide perovskite) nanocrystallinestructure according to one exemplary embodiment of the present inventionincludes an organic ammonium (or an alkali metal) and halides.

Referring again to FIG. 1D, a second electrode 50 is formed on theaforementioned light emitting layer 40.

The aforementioned second electrode 50 is an electrode in whichelectrons are injected, and is composed of a material having aconductive property. The aforementioned second electrode 50 ispreferably a metal, and may be particularly Al, Au, Ag, Cu, Pt, W, Ni,Zn, Ti, Zr, Hf, Cd, Pd, etc.

As a deposition process for forming the aforementioned second electrode50, physical vapor deposition (PVD), chemical vapor deposition (CVD),sputtering, pulsed laser deposition (PLD), thermal evaporation, electronbeam evaporation, atomic layer deposition (ALD), molecular beam epitaxy(MBE), and the like may be used.

The light emitting device thus formed includes a first electrode 20, anexciton buffer layer 30 disposed on the aforementioned first electrode20 and including a conductive material and a fluorine-based material, alight emitting layer 40 disposed on the aforementioned exciton bufferlayer 30 and including an organic-inorganic-hybrid perovskitenanoparticle light-emitter with which an organic ligand is substituted,and a second electrode 50 disposed on the aforementioned light emittinglayer 40.

In this case, a light emitting device having a low work function andhigh conductivity as well may be manufactured as the aforementionedexciton buffer layer 30 is formed. In the nanoparticle light-emitterincluding the organic-inorganic-hybrid perovskite nanocrystals, anorganic-inorganic-hybrid perovskite having a combined FCC and BCCcrystalline structure in the nanoparticle light-emitter may be formed, alamellar structure in which an organic plane and an inorganic plane arealternatively deposited may be formed, and excitons can be confined tothe inorganic plane, thereby expressing high color purity.

The inorganic metal halide perovskite light emitting device according toone exemplary embodiment of the present invention will be described.

The light emitting device may include a first electrode, an excitonbuffer layer disposed on the first electrode and including a conductivematerial and a fluorine-based material having lower surface energy thanthe conductive material, a light emitting layer disposed on the excitonbuffer layer and including an inorganic metal halide perovskitematerial, and a second electrode disposed on the light emitting layer.

The exciton buffer layer is characterized by being configured so that aconductive layer including the conductive material and a surface bufferlayer including the fluorine-based material having lower surface energythan the conductive material are sequentially deposited. The surfacebuffer layer is characterized by having a thickness of 3 nm or more. Theexciton buffer layer is characterized by having a conductivity of 10⁻⁷S/cm to 1,000 S/cm. The fluorine-based material is characterized byhaving a surface energy of 30 mN/m or less.

A specific description of the inorganic metal halide perovskite lightemitting device is the same as in the organic-inorganic-hybridperovskite light emitting device, and thus a repeated descriptionthereof is omitted.

By way of another example, a photoactive layer including theaforementioned organic/inorganic perovskite nanocrystals or inorganicmetal halide perovskite nanocrystals may also be applied to a solarcell. Such a solar cell may include a first electrode, a secondelectrode, a photoactive layer interposed between the first electrodeand the second electrode and including the aforementioned perovskitecolloidal nanoparticles, and an exciton buffer layer.

Hereinafter, preferred embodiments of the present invention will bepresented to aid in understanding the present invention. However, itshould be understood that the following examples are merely provided toaid in understanding the present invention, but not intended to limitthe scope of the present invention.

MODE FOR INVENTION Preparative Example 1

A light emitting device according to one exemplary embodiment of thepresent invention was manufactured.

First, an ITO substrate (a glass substrate coated with an ITO positiveelectrode) was prepared, and a solution obtained by mixing PEDOT:PSS(CLEVIOS PH commercially available from Heraeus) as a conductivematerial and a material of the following Polymer 1 as a fluorine-basedmaterial was then spin-coated onto the ITO positive electrode.Thereafter, the solution was thermally treated at 150° C. for 30 minutesto form an exciton buffer layer having a thickness of 40 nm.

After the thermal treatment, a multilayer exciton buffer layer in whicha conductive layer containing more than 50% of the conductive polymerand a surface buffer layer containing more than 50% of theaforementioned material of Polymer 1 were sequentially deposited wasformed on the aforementioned ITO positive electrode. That is, theconductive layer and the surface buffer layer were formed throughself-assembly.

The exciton buffer layer including the aforementioned conductive layerand the surface buffer layer included PEDOT, PSS and Polymer 1 at aweight ratio of 1:6:25.4 and had a work function of 5.95 eV.

A solution (40% by weight) including CH₃NH₃PbBr₃ and dimethyl formamidewas spin-coated onto the aforementioned exciton buffer layer, andthermally treated at 90° C. for 10 minutes to form a CH₃NH₃PbBr₃perovskite light emitting layer having a thickness of 150 nm. Such aCH₃NH₃PbBr₃ perovskite light emitting layer had a HOMO energy level of−5.9 eV, and a surface of a second layer in the aforementioned bufferlayer had a work function of −5.95 eV.

Next, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI) having athickness of 50 nm was deposited on the light emitting layer under ahigh vacuum of 1×10⁻⁷ Torr or less to form an electron transport layer,LiF having a thickness of 1 nm was deposited on the electron transportlayer to form an electron injection layer, and aluminum having athickness of 100 nm was deposited on the electron injection layer toform a negative electrode, thereby manufacturing anorganic-inorganic-hybrid perovskite light emitting device.

Preparative Example 2

An organic-inorganic-hybrid perovskite light emitting device wasmanufactured in the same manner as in Preparative Example 1, except thatthe formed exciton buffer layer included PEDOT, PSS and Polymer 1 at aweight ratio of 1:6:12.7 and had a work function of 5.79 eV.

Preparative Example 3

An organic-inorganic-hybrid perovskite light emitting device wasmanufactured in the same manner as in Preparative Example 1, except thatthe formed exciton buffer layer included PEDOT, PSS and Polymer 1 at aweight ratio of 1:6:6.3 and had a work function of 5.72 eV.

Preparative Example 4

An organic-inorganic-hybrid perovskite light emitting device wasmanufactured in the same manner as in Preparative Example 1, except thatthe formed exciton buffer layer included PEDOT, PSS and Polymer 1 at aweight ratio of 11:6:3.2 and had a work function of 5.63 eV.

Preparative Example 5

An organic-inorganic-hybrid perovskite light emitting device wasmanufactured in the same manner as in Preparative Example 1, except thatthe formed exciton buffer layer included PEDOT, PSS and Polymer 1 at aweight ratio of 1:6:1.6 and had a work function of 5.55 eV.

Comparative Example 1

An organic-inorganic-hybrid perovskite light emitting device wasmanufactured in the same manner as in Preparative Example 1, except thata single-layer buffer layer (having a work function of 5.20 eV) having athickness of 40 nm was formed by spin-coating the aforementionedPEDOT:PSS (CLEVIOS PH commercially available from Heraeus) solution ofPreparative Example 1 onto an ITO positive electrode and thermallytreating the PEDOT:PSS solution at 150° C. for 30 minutes in order toform an exciton buffer layer. That is, in this case, the buffer layerwas a PEDOT:PSS layer.

FIG. 7 is a schematic diagram (a) and an SEM image (b) of the lightemitting device manufactured in Preparative Example 1 of the presentinvention.

Referring to FIG. 7, it can be seen that the light emitting deviceaccording to one exemplary embodiment of the present invention includedthe first electrode, the exciton buffer layer, the light emitting layerincluding the organic-inorganic-hybrid perovskite, and the secondelectrode, which were uniformly formed in this order.

FIGS. 8A to 8D are graphs illustrating current-voltage characteristics(a), brightness-voltage characteristics (b), current efficiency-voltagecharacteristics (c), and external quantum efficiency-voltagecharacteristics (d) of each of the light emitting devices of PreparativeExamples 1 to 5 and Comparative Example 1.

Referring to FIGS. 8A to 8D, it can be seen that the brightness, currentefficiency and external quantum efficiency of the light emitting devicewere enhanced as the PFI (a fluorine-based material of Polymer 1) wasincluded in the exciton buffer layer and a weight ratio of theaforementioned PFI increased.

Preparative Example 6

First, a glass substrate was prepared, and a solution obtained by mixingPEDOT:PSS (CLEVIOS PH commercially available from Heraeus) as theconductive material and the aforementioned material of Polymer 1 as thefluorine-based material was then spin-coated onto the glass substrate,and thermally treated at 150° C. for 30 minutes to form an excitonbuffer layer having a thickness of 40 nm.

After the thermal treatment, a multilayer exciton buffer layer in whicha conductive layer containing more than 50% of the conductive polymerand a surface buffer layer containing more than 50% of theaforementioned material of Polymer 1 were sequentially deposited wasformed on the aforementioned glass substrate. That is, the conductivelayer and the surface buffer layer were formed through self-assembly.

The exciton buffer layer including the aforementioned conductive layerand the surface buffer layer included PEDOT, PSS and Polymer 1 at aweight ratio of 1:6:25.4 and had a work function of 5.95 eV.

A solution (0.6% by weight) including CH₃NH₃PbBr₃ and dimethyl formamidewas spin-coated onto the aforementioned exciton buffer layer, andthermally treated at 90° C. for 10 minutes to form a CH₃NH₃PbBr₃perovskite light emitting layer having a thickness of 10 nm.

Such a CH₃NH₃PbBr₃ perovskite light emitting layer had a HOMO energylevel of −5.9 eV, and a surface of a second layer in the aforementionedbuffer layer had a work function of −5.95 eV. Because a thin film samplehaving the light emitting layer rather than the light emitting deviceexposed at a top portion thereof was required to check the lifetimecharacteristics of the light emitting layer, a deposition process wasnot carried out.

Preparative Example 7

An organic-inorganic-hybrid perovskite thin film sample was formed inthe same manner as in Preparative Example 6, except that the formedexciton buffer layer included PEDOT, PSS and Polymer 1 at a weight ratioof 1:6:12.7 and had a work function of 5.79 eV.

Preparative Example 8

An organic-inorganic-hybrid perovskite thin film sample was formed inthe same manner as in Preparative Example 6, except that the formedexciton buffer layer included PEDOT, PSS and Polymer 1 at a weight ratioof 1:6:6.3 and had a work function of 5.72 eV.

Preparative Example 9

An organic-inorganic-hybrid perovskite thin film sample was formed inthe same manner as in Preparative Example 6, except that the formedexciton buffer layer included PEDOT, PSS and Polymer 1 at a weight ratioof 1:6:1.6 and had a work function of 5.55 eV.

Comparative Example 2

An organic-inorganic-hybrid perovskite thin film sample was manufacturedin the same manner as in Preparative Example 6, except that asingle-layer buffer layer (having a work function of 5.20 eV) having athickness of 40 nm was formed by spin-coating the aforementionedPEDOT:PSS (CLEVIOS PH commercially available from Heraeus) solution ofPreparative Example 6 onto an ITO positive electrode and thermallytreating the PEDOT:PSS solution at 150° C. for 30 minutes in order toform an exciton buffer layer. That is, in this case, the buffer layerwas a PEDOT:PSS layer.

Preparative Example 10: Preparation of Inorganic Metal Halide PerovskiteColloidal Nanoparticles

Inorganic metal halide perovskite colloidal nanoparticles according toone exemplary embodiment of the present invention were formed. Here, theinorganic metal halide perovskite colloidal nanoparticles were formedusing an inverse nano-emulsion method.

Specifically, cesium carbonate (Cs₂CO₃) and oleic acid were added tooctadecene (ODE) serving as an aprotic solvent, and reacted at a hightemperature to prepare a third solution. PbBr₂, oleic acid andoleylamine were added to an aprotic solvent, and reacted at a hightemperature (120° C.) for an hour to prepare a fourth solution.

Next, the third solution was added dropwise to the fourth solution whilestrongly stirring to form an inorganic metal halide perovskite (CsPbBr₃)colloidal nanoparticle light-emitter having a 3D structure.

Therefore, a solution including the inorganic metal halide perovskitenanoparticles was prepared.

Preparative Example 11

A light emitting device was manufactured in the same manner as inPreparative Example 1, except that a solution (40% by weight) includingCsPbBr₃ prepared in Preparative Example 10 and dimethyl formamide wasspin-coated onto an exciton buffer layer, and thermally treated at 90°C. for 10 minutes to form a CsPbBr₃ inorganic metal halide perovskitelight emitting layer having a thickness of 150 nm.

Preparative Example 12

A solar cell according to one exemplary embodiment of the presentinvention was manufactured.

First, an ITO substrate (a glass substrate coated with an ITO positiveelectrode) was prepared, and a hole extraction layer was then formed onthe ITO positive electrode using a method for manufacturing theaforementioned exciton buffer layer.

An organic-inorganic-hybrid perovskite thin film according toPreparative Example 1 was formed on the hole extraction layer, and thencoated with phenyl-C61-butyric acid methyl ester (PCBM) to form aphotoactive layer. Thereafter, Al having a thickness of 100 nm wasdirectly deposited on the photoactive layer to prepare a perovskitesolar cell using an exciton buffer layer.

Experimental Example: Analysis of Lifetime Characteristics andPhotoluminescence Characteristics of Light Emitting Devices

To analyze exciton lifetime characteristics and photoluminescencecharacteristics of the organic-inorganic-hybrid perovskite thin filmsamples manufactured in Preparative

Examples 6 to 9 and Comparative Example 2, time-resolvedphotoluminescence (TR-PL) measurement was performed. Each of the sampleswas excited by a Ti:sapphire laser having a wavelength of 350 nm, apulse duration of 150 fs, and a repetition rate of 80 MHz. The PLlifetime was measured at 530 nm and 300 K using a streak camera.

FIG. 9 is a graph illustrating PL lifetime characteristics and strengthcharacteristics of the light emitting devices of Preparative Examples 6to 9 of the present invention and Comparative Example 2.

Referring to FIGS. 9(a) and 9(b), the average PL lifetimes were measuredto be 4.7 ns, 0.46 ns, 0.42 ns, 0.39 ns, and 0.34 ns in the case ofPreparative Example 6, Preparative Example 7, Preparative Example 8,Preparative Example 9, and Comparative Example 2, respectively.

In conclusion, it was confirmed that the average PL lifetime increasedwith an increasing weight ratio of PFI. This was because PFI (Polymer 1)on a surface of the exciton buffer layer serves as a buffer forpreventing the quenching of excitons. Also, in the case of the PFI-freePEDOT:PSS buffer layer (Comparative Example 2), the excitons in aperovskite layer were able to be quenched via non-radiative energytransfer generated due to a difference in energy level between twolayers. In this case, the average PL lifetime of the excitons decreased.

Also, it can be seen that the intensity of PL was also able to increasewith an increasing weight ratio of the aforementioned PFI.

Preparative Example 10

An organic-inorganic-hybrid perovskite light emitting device wasmanufactured in the same manner as in Example 1, except that thefollowing Polymer 2 was used as the fluorine-based material to form theexciton buffer layer.

Although the present invention have been shown and described withreference to the preferred embodiments thereof, it would be appreciatedby those skilled in the art that changes and modifications may be madein these embodiments without departing from the principles and spirit ofthe disclosure, the scope of which is defined in the claims and theirequivalents.

Brief Description of Parts in Drawings

10: substrate 20: first electrode 30: exciton buffer layer 31:conductive layer 32: surface buffer layer 40: light emitting layer 50:second electrode

The invention claimed is:
 1. A light-emitting device comprising: a firstelectrode; a second electrode; at least one exciton buffer layercomprising at least one conductive material and at least onefluorine-based material having lower surface energy than the conductivematerial, wherein the exciton buffer layer between the first electrodeand the second electrode can prevent the quenching of excitons; at leastone light-emitting layer comprising a perovskite material between thefirst electrode and the second electrode.
 2. The light emitting deviceof claim 1, wherein the conductive material comprises at least oneselected from the group consisting of a conjugated conductive polymer, ametallic carbon nanotube, graphene, a reduced graphene oxide, metalnanowires, semiconductor nanowires, carbon nanodots, metal nanodots, anda conductive oxide.
 3. The light emitting device of claim 1, wherein thefluorine-based material is an ionomer comprising at least one F element.4. The light emitting device of claim 1, wherein the exciton bufferlayer has a conductivity of 10⁻⁷ S/cm to 1,000 S/cm.
 5. The lightemitting device of claim 1, wherein the fluorine-based material has asurface energy of 30 mN/m or less.
 6. The light emitting device of claim1, wherein the emitting layer includes at least one selected from thegroup consisting of a thin film comprising a perovskite material in aform of particle or nanocrystalline structure, a perovskite thin filmprocessed from a perovskite solution that is dissolved in solvent, and aperovskite thin film processed from a perovskite solution that isdispersed in solvent.
 7. The light emitting device of claim 1, whereinthe perovskite has a structure of A₂BX₄, ABX₄, ABX₃ orA_(n−1)B_(n)X_(3n+1) (where n is an integer ranging from 2 to 6),wherein A is an organic ammonium material or alkali metal, B is a metalmaterial, and X is a halogen element.
 8. The light emitting device ofclaim 1, wherein a hole or electron transport layer is formed adjacentto the exciton buffer layer.
 9. The light emitting device of claim 1,wherein an electron transport layer comprises1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI) or itsderivatives.
 10. The light emitting device of claim 1, wherein an holetransport layer is at least one selected from the group consisting of1,3-bis(carbazol-9-yl)benzene (MCP), 1,3,5-10 tris(carbazol-9-yl)benzene(TCP), 4,4′,4″ -tris(carbazol-9-yl)triphenylamine (TCTA),4,4′bis(carbazol-9-yl)biphenyl (CBP), N,N′ -bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzidine (NPB), N,N′ -bis(naphthalen-2-yl)-N,N′-bis(phenyl)-benzidine (˜-NPB), N,N′- bis(naphthalen-1-yl)-N,N′-bis(phenyl)-2,2′ -dimethylbenzidine (a-NPD), di-[4,-(N,Nditolyl-amino)-phenyl]cyclohexane (T APC), N,N,N′ ,N′-tetra-naphthalen-2-yl-benzidine 15 (˜-TNB) and N4,N4,N4′ ,N4′-tetra(biphenyl-4-yl)biphenyl-4,4′ -diamine (TPDI5),poly(9,9-dioctylfluorene-co-bis-N,N′ -(4-butyl phenyl)-bis-N,N′-phenyl-I, 4- phenylenediamine) (PFB), poly(9,9′-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB), pol y(9, 9′-dioctylfluorene-co-bis-N,N′ -(4-butyl phenyl)-bis-N,N′ -phenylbenzidine) (BFB), poly(9,9-dioctylfluorene-co-bis-N,N′-(4-methoxyphenyl)-bis-N,N′ -phenyl-1 ,4- 20 phenylenediamine) (PFMO),and their derivatives.
 11. The light emitting device of claim 1, whereinthe electrode is conductive metal oxide which is at least one selectedfrom the group consisting of indium tin oxide (ITO), metal, AI-doped ZnO(AZO), Ga-doped ZnO (GZO), IniGa-doped ZnO (IGZO), Mg-doped ZnO (MZO),Mo-doped ZnO, AI-doped MgO, Ga-doped MgO, F-doped Sn O₂, Nb-doped TiO₂,and CuAIO.
 12. The light emitting device of claim 1, wherein thefluorine-based material comprises at least one ionomer selected from thegroup consisting of ionomers having structures represented by thefollowing Formulas 1 to 12:

wherein m is a number ranging from 1 to 10,000,000, x and y are eachindependently a number ranging from 0 to 10, and M⁺ represents Na⁺, K⁺,Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50),N₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where Rrepresents CH₃(CH₂)_(n−), where n is an integer ranging from 0 to 50);

wherein m is a number ranging from 1 to 10,000,000;

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are eachindependently a number ranging from 0 to 20, and M⁺ represents Na⁺, K⁺,Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50),N₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where Rrepresents CH₃(CH₂)_(n−), where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are eachindependently a number ranging from 0 to 20, M⁺ represents Na⁺, K⁺, Li⁺,H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50), N₄⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where Rrepresents CH₃(CH₂)_(n−), where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, z is a numberranging from 0 to 20, and M⁺ represents Na⁺, K⁺, Li⁺, H⁺,CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50), NH₄ ⁺,NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where R representsCH₃(CH₂)_(n−), where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are eachindependently a number ranging from 0 to 20, Y represents one selectedfrom —COO⁻M⁺, —SO₃ ⁻NHSO₂CF₃ ⁺, and —PO₃ ²⁻(M⁺)₂, and M⁺ represents Na⁺,K⁺, Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to50), NH₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, and RCHO⁺ (Rrepresents CH₃(CH₂)_(n−), where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, and M⁺ representsNa⁺, K⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to50), NH₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where Rrepresents CH₃(CH₂)_(n−), where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000;

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x is a numberranging from 0 to 20, and M⁺ represents Na⁺, K⁺, Li⁺, H⁺,CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50), NH₄ ⁺,NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where R representsCH₃(CH₂)_(n−), where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are eachindependently a number ranging from 0 to 20, and M⁺ represents Na⁺, K⁺,Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integer ranging from 0 to 50),NH₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where Rrepresents CH₃(CH₂)_(n−), where n is an integer ranging from 0 to 50);

wherein m and n are 0≤m<10,000,000 and 0<n≤10,000,000, R_(f)═—(CF₂)_(z)—(where z is an integer ranging from 1 to 50, provided that 2 isexcluded), —(CF₂CF₂O)_(z)CF₂CF₂— (where z is an integer ranging from 1to 50), —(CF₂CF₂CF₂O)_(z)CF₂CF₂— (where z is an integer ranging from 1to 50), and M⁺ represents Na⁺, K⁺, Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where nis an integer ranging from 0 to 50), NH₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺,C₂H₅OH⁺, CH₃OH⁺, or RCHO⁺ (where R represents CH₃(CH₂)_(n−), where n isan integer ranging from 0 to 50); and

wherein m and n are 0≤m<10,000,000 and 0<n≤10,000,000, x and y are eachindependently a number ranging from 0 to 20, Y represents one selectedfrom —SO₃ ⁻M⁺, —COO⁻M⁺, —SO₃ ⁻NHSO₂CF₃ ⁺, and —PO₃ ²⁻(M⁺)₂, and M⁺represents Na⁺, K⁺, Li⁺, H⁺, CH₃(CH₂)_(n)NH₃ ⁺ (where n is an integerranging from 0 to 50), N₄ ⁺, NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺,or RCHO⁺ (where R represents CH₃(CH₂)_(n−), where n is an integerranging from 0 to 50).
 13. The light emitting device of claim 1, whereinthe fluorine-based material comprises at least one ionomer orfluorinated oligomer selected from the group consisting of ionomers orfluorinated oligomers having structures represented by the followingFormulas 13 to 19:

wherein R₁₁ to R₁₄, R₂₁ to R₂₈, R₃₁ to R₃₈, R₄₁ to R₄₈, R₅₁ to R₅₈, andR₆₁ to R₆₈ are each independently selected from hydrogen, —F, a C₁-C₂₀alkyl group, a C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkyl group substitutedwith one or more —F radicals, a C₁-C₂₀ alkoxy group substituted with oneor more —F radicals, Q₁, —O—(CF₂CF(CF₃)—O)_(n)—(CF₂)_(m)-Q₂ (where n andm are each independently an integer ranging from 0 to 20, provided thatthe sum of n and m is greater than or equal to 1), and —(OCF₂CF₂)_(x)-Q₃(where x is an integer ranging from 1 to 20), where Q₁ to Q₃ representan ion group, where the ion group comprises an anionic group and acationic group, the anionic group is selected from PO₃ ²⁻, SO₃ ⁻, COO⁻,I⁻, CH₃COO⁻, and BO₂ ²⁻, the cationic group comprises one or more of ametal ion and organic ion, the metal ion is selected from Na⁺, K⁺, Li⁺,Mg⁺², Zn⁺², and Al⁺³, and the organic ion is selected from H⁺,CH₃(CH₂)_(n1)NH₃ ⁺ (where n1 is an integer ranging from 0 to 50), NH₄ ⁺,NH₂ ⁺, NHSO₂CF₃ ⁺, CHO⁺, C₂H₅OH⁺, CH₃OH⁺, and RCHO⁺ (where R representsCH₃(CH₂)n²⁻, and n₂ is an integer ranging from 0 to 50); wherein atleast one of R₁₁ to R₁₄, at least one of R₂₁ to R₂₈, at least one of R₃₁to R₃₈, at least one of R₄₁ to R₄₈, at least one of R₅₁ to R₅₈, and atleast one of R₆₁ to R₆₈ are selected from —F, a C₁-C₂₀ alkyl groupsubstituted with one or more —F radicals, a C₁-C₂₀ alkoxy groupsubstituted with one or more —F radicals,—O—(CF₂CF(CF₃)—O)_(n)—(CF₂)_(m)-Q₂, and —(OCF₂CF₂)_(x)-Q₃; andX-M^(f) _(n)-M^(h) _(m)-M^(a) _(r)-G   <Formula 19> wherein X representsan end group; M^(f) represents a unit derived from a fluorinated monomerobtained by condensation reaction of perfluoropolyether alcohol,polyisocyanate, and an isocyanate-reactive non-fluorinated monomer;M^(h) represents a unit derived from a non-fluorinated monomer; M^(a)represents a unit having a silyl group represented by —Si(Y₄)(Y₅)(Y₆),where Y₄, Y₅ and Y₆ each independently represent a substituted orunsubstituted C₁-C₂₀ alkyl group, a substituted or unsubstituted C₆-C₃₀aryl group, or a hydrolysable substituent, provided that at least one ofY₄, Y₅ and Y₆ is the hydrolysable substituent; G is a monovalent organicgroup including a residue of a chain transfer agent; n is a numberranging from 1 to 100; m is a number ranging from 0 to 100; and r is anumber ranging from 0 to 100; provided that the sum of n, m and r is atleast
 2. 14. The light emitting device of claim 1, wherein theconductive material comprises at least one selected from the groupconsisting of a conductive polymer, a metallic carbon nanotube,graphene, a reduced graphene oxide, metal nanowires, semiconductornanowires, carbon nanodots, metal nanodots, and a conductive oxide. 15.The emitting layer of claim 6, wherein a perovskite material in a formof particle or nanocrystalline structure is comprising a plurality ofligand or surfactant surrounding the perovskite nanocrystals.
 16. Theemitting layer of claim 6, wherein perovskite thin films were preparedby perovskite solution is at least one polar solvent selected from thegroup consisting of water, an alcohol (methanol, ethanol, n-propanol,2-propanol, n-butanol, etc.), formic acid, nitromethane, acetic acid,ethylene glycol, glycerol, n-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide, dimethyl formamide (DMF), dimethyl sulfoxide (DMSO),tetrahydrofuran (THF), ethyl acetate (EtOAc), acetone, and acetonitrile(MeCN).
 17. The light emitting device of claim 7, wherein A is at leastone selected from the group consisting of (CH₃NH₃)_(n),((C_(x)H_(2x+1))_(n)NH₃)₂(CH₃NH₃)_(n), (RNH₃)₂, (C_(n)H_(2n+1)NH₃)₂,(CF₃NH₃), (CF₃NH₃)_(n), ((C_(x)F_(2x+1))_(n)NH₃)₂(CF₃NH₃)_(n),((C_(x)F_(2x+1))_(n)NH₃)₂, alkali metal or (C_(n)F_(2n+1)NH₃)₂ (where nis an integer greater than or equal to 1, and x is an integer greaterthan or equal to 1, R is H or a C1-C10 alkyl group) B is at least oneselected from the group consisting of a divalent transition metal, arare earth metal, an alkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb,Bi, and Po, and X is at least one selected from the group consisting ofCl, Br, and I.
 18. The conductive materials of claim 14, wherein theconductive polymer comprises at least one selected from the groupconsisting of polythiophene, polyaniline, polypyrrole, polystyrene,sulfonated polystyrene, poly(3,4-ethylene dioxythiopene), a self-dopedconductive polymer, and a derivative thereof.
 19. The light emittingdevice of claim 1, which was fabricated using at least one methodselected from the group consisting of vacuum deposition method, aspin-coating method, a casting method, and an LB method.
 20. A solarcell comprising: a first electrode; a second electrode; at least oneexciton buffer layer comprising at least one conductive material and atleast one fluorine-based material having lower surface energy than theconductive material; at least one photoactive layer comprising aperovskite material between the first electrode and the secondelectrode; wherein the perovskite material is in a form of particles,nanocrystalline structures, or thin films having nanocrystals.